BAGHDAD Insurgents targeted passenger buses north of Baghdad on Tuesday, as a suicide bomber killed at least eight people west of Mosul and gunmen seized 21 men traveling through Diyala province.
The latest bloodshed highlighted the slow-going, punch-counterpunch U.S.-led campaign against al-Qaida in Iraq, more than a month after Iraq's prime minister said he expected the fight for Mosul would be a "decisive battle."
The Americans view the northern campaign as a chance to subdue al-Qaida in Iraq in areas surrounding Mosul, a major transportation hub which the military has described as the terror group's last urban stronghold.
Tuesday's bombing, 40 miles west of Mosul, struck a bus heading from that city to the Syrian capital of Damascus.
Al-Qaida is believed to use the cover of sprawling sheep and produce markets in Mosul to smuggle foreign fighters, weapons and cash from Syria. Mosul, the country's third-largest city, lies some 80 miles east of the Syrian border and 225 miles northwest of Baghdad.
Farther north, Turkish officials said Tuesday their troops pressed an incursion deeper into Iraq, as they chased separatist Kurdish rebels as much as 12 miles across that border. Fed-up Iraqi leaders demanded that Turkey end the military operation, and the regional parliament in Iraq's semiautonomous Kurdish area unanimously approved a measure authorizing its military forces to fight back if attacked by Turks.
The south, however, was relatively calm. There, millions of black-clad pilgrims clogged the streets of Karbala for the peak of an annual religious commemoration for a revered Shiite figure. A nationwide pilgrimage to the city was marred by attacks earlier in the week that killed at least 63 people.
Violence has rattled much of the northern region in recent days.
The U.S. military said it killed seven al-Qaida in Iraq members and captured three insurgents during a firefight Monday east of the town of Khan Bani Saad, near the Diyala provincial capital of Baqouba. Three soldiers were wounded, it said.
Elsewhere in Diyala, police said gunmen in civilian clothes stopped two buses at a fake checkpoint on a highway in the Adeim area, 45 miles north of Baqouba, then took the buses and kidnapped 21 men. They later released three women, said an officer, who spoke on condition of anonymity because he wasn't authorized to release the information.
Police said the gunmen seized the buses while they were heading south to Baqouba, northeast of Baghdad, from the city of Kirkuk.
Iraqi army and U.S. military versions of the bus bombing varied somewhat, with the Iraqis saying that nine people were killed and eight wounded, and the U.S. authorities placing the death toll at eight, with eight wounded.
The Iraqis said the blast took place after the bomber told the bus driver to divert from the highway and avoid checkpoints. The driver refused. Brig. Gen. Khalid Abdul-Sattar said the suicide bomber then detonated himself when the bus was about 200 yards from a checkpoint.
However, the U.S. military said the attack occurred at a routine checkpoint where the Iraqi army was searching passengers for their identity cards. After the bomber exited the bus, he detonated a suicide vest, the military said.
Iraqi Prime Minister Nouri al-Maliki once described the fight for Mosul as a "decisive battle" against the Sunni radical group. But the U.S. military has tried to temper expectations of a climactic showdown, describing the effort as more of steady push than a single battle. U.S. Ambassador to Iraq Ryan Crocker has termed it a "hard fight."
Meanwhile Tuesday, tension surrounding Turkey's incursion into Iraq rose as the Iraqi Cabinet demanded the Turks end their current campaign against the Kurdistan Workers' Party, or PKK.
The PKK, which the U.S. considers a terrorist group, wants autonomy for the predominantly Kurdish southeastern Turkey. Rebels have carried out attacks in Turkey from bases in Kurdish Iraq in a conflict that dates back to 1984.
A Turkish delegation will meet Wednesday with Iraqi President Jalal Talabani, Foreign Minister Hoshyar Zebari, both Kurds, as well as other top Iraqi officials, government spokesman Ali al-Dabbagh said.
Turkey has assured the Iraqi government and the U.S. military that the operation would be limited to attacks on rebels.
But al-Dabbagh warned the tensions could escalate if Kurdish security forces, the peshmerga, were drawn into the fight.
"We want good relations with Turkey, and Turkey should understand that the situation is dangerous and could be made worse by any military mistake that could prompt clashes between the peshmerga and Turkish troops," al-Dabbagh said. "Then the military intervention might be widened and civilians might be endangered and infrastructure damaged."
In Karbala, 50 miles south of Baghdad, the annual spectacle of Arbaeen was on display Tuesday under heavy security.
The commemoration marks the end of the mourning period following the anniversary of the death of Imam Hussein, who was slain in a seventh century battle and is buried in Karbala.
Associated Press Television News footage showed processions of men, some barefoot, marching in time and flagellating themselves to the beat of a drum. Crowds of black-robed women five or six deep watched from the side and tapped themselves over the heart.
Iraqi and U.S. authorities have said at least 8 million pilgrims will join the ceremonies by the time they reach their peak Wednesday and Thursday. They will be joined by 40,000 troops, snipers and plainclothes security officers.
"I came 10 days ahead of time to serve the pilgrims of Imam Hussein, defying all circumstances and terrorist acts," said 62-year-old pilgrim Mohammed Hussein.
Associated Press writers Sinan Salaheddin and Hamid Ahmed contributed to this report.